For 35 years, Toronto-based law firm Cassels Brock & Blackwell was housed in a 10,000-square-metre office in Toronto’s financial district. Like many 1980s-era workplaces, it had long corridors, compact cubicles, status-affirming corner offices and a deficit of natural light—functional but not exactly a place where anyone would want to spend 40-plus hours a week. In 2019, the firm was growing its workforce and needed a bigger space, so its leaders decided to relocate to a 12,500-square-metre...